Investigation of the effect of different adjuvants on felodipine release kinetics from sustained release monolithic films

A transdermal film was developed employing a calcium channel blocker, felodipine, with two acrylic resin polymers of varying permeability (Eudragit RL 100 and RS 100). The drug and two acrylic co-polymers of different permeabilities at ratio 1:1, with and without adjuvants were used to form films. Adjuvants, including polyethylene glycols (PEG 200, 400, 600, 1000), glycerol, ethoxydiglycol and propylene glycol were incorporated into films. The effect of these adjuvants on the release of drug from the films was investigated by the USP Method Apparatus II. The release data were evaluated kinetically using a computer programme (DISSOL). Drug release from the formulations containing 10% adjuvants showed zero order kinetics. The release profiles of the films which contained 10% glycerol and ethoxydiglycol were in most agreement with the target profile that was plotted based on the pharmacokinetic parameters. The relationship between the in vitro drug release data and moisture permeation constant and glass transition temperature was investigated. The in vitro release rate of drug increased with increasing water vapor transmission. No relationship was established between glass transition temperature values of the films and in vitro release of drug.